Electrochemical Detection Research For Single Nucleotide Polymorphisms

Disorders in gene fragments with the emergence of genetic diseases are closely related, of which single nucleotide polymorphisms (SNPs) in the human genome is the most common genetic variation. Thus, SNPs detection of the molecular basis of genetic disease research, clinical diagnosis and treatment is of great significance, to become today's analytical chemistry and life sciences in the forefront of the field of interdisciplinary research. Because of its higher sensitivity and the characteristics of simplicity, electrochemical assay methods are also widely used in the life sciences research. In this paper, we focuse on electrochemical methods research for the detection of SNPs genotyping, and achieves the goal of quick, sensitive, and accurate assay of the target. The details are as follows:1. A novel electrochemical detection method for SNP genotyping was developed combined with high-loyalty of DNA ligase as well as the catalytic effect of streptavidin alkaline phosphatase (SA-ALP). The thiol-modified capture probe and the biotin-labeled probe hybridized with the target sequence in suitable conditions. The ligation reaction can be carried out favourably only when the sequences were exactly matched, then electrochemical signal can be obtained through linear sweep voltammetry (LSV) after enzyme-catalyzed silver deposition. Contrarily, no ligation reaction occurred and no signal can be produced if there was single base mutation in the target sequence. Then we can achieve the distinction of gene mutation.2. The primer extension (PEXT) reaction is one of the methods most commonly used in genotyping of SNP. Owing to the high specificity of PEXT, the extension reaction can be performed favorably only when the primer and target DNA were perfectly matched. The ferrocene can be incorporated in the extension product by primer extension reaction, which was then captured by the capture probe self-assembled on the electrode surface. Differential pulse voltammetry (DPV) was used to detect the presence of the ferrocene in close proximity of the gold electrode surface. Furthermore, this proposed method was successfully applied to the genotyping of SNPs atβ-Thalassemia (CD28). The detection limit of this method can be reached down to 0.86 fM and the experimental results show that it is a simple, speedy and sensitive approach for genotyping of SNP.3. On the basis of the principle analogous to the second work, combinded with the high specificity of PEXT and CdS, PbS particals, a sensitive electrochemical approach for SNP genotyping was established in this part by the way of electrochemical deposition and dissolution of metal. In the whole analysis procedure, there were mainly three parts: primer extension reaction, hybridization reaction, electrochemical detection.